It is known to use as a base of different building materials, such as floor or wall coverings, roofing felts etc., a felt-like material for effecting sound/or thermal insulation. Especially good step sound dampening properties and also thermal insulation capability as well as capability of protecting constructions from possible fire are required particularly in the case of floor and wall coverings. Same properties, especially concerning the fire protection, are required in the case of roofing felts.
The webs in question and building materials having such webs as their bases, as well as other manufacturing methods of the same are widely discussed in patent literature, for example in European Patent Application 176,847 (Hoechst AG), German Offenlegungsschrift 1,919,709 (Saint Gobain), German Offenlegungsschrift 3,226,041 (Didier-Werken AG), U.S. Pat. No. 4,657,801 (Hoechst AG), British Patent 1,532,621 (Nairn Floors Ltd.), German Offenlegungsschrift 3,017,018 (GAF Corporation) and U.S. Pat. No. 4,175,514 (GAF Corporation).
Said patents and patent applications disclose webs and products manufactured therefrom having no optimal strength, thermal insulation and fire protection properties nor processability in manufacture.
U.S. Pat. No. 4,522,876 (Lydall, Inc.) shows a mat comprising at least one organic fiber layer and at least one glass fiber layer. The layers are bound together by needling. The mat is used as a heat insulator to be placed between the floor board of an automobile and the carpet of an automobile. The organic fiber layer is relatively thin, and functions mainly as a strength component and containment of the glass fibers of the glass fiber layer.